The present invention pertains to topical preparations comprising benzoyl peroxide and clindamycin, which are used for treating skin disorders involving the sebaceous glands and follicles in humans.
Skin disorders involving the sebaceous glands and follicles in humans include conditions such as acne and rosacea, as well as other noninfectious dermatological diseases involving microorganisms. Such disorders are often marked by inflammation.
In the past, these dermatological disorders have been treated with oral and/or topical antibacterial agents. The oral antibiotics used include tetracycline, erythromycin and minocycline. The topical compositions used have separately contained the antibiotics tetracycline, erythromycin and clindamycin, as well as benzoyl peroxide, which exerts its antibacterial action via its potent oxidizing properties. However, it is the strong oxidizing properties of peroxide that results in unstable compositions. Benzoyl peroxide also can act as a sebosuppressant, an irritant, and comedolytic agent.
Topical compositions which combine at least two active antibacterial agents have been proposed as a treatment to these disorders. These compositions require compounding by the pharmacist and must be refrigerated. After three months of refrigeration, the compositions lose potency and effectiveness and must be replaced with a new batch.
For example, a currently-available combination product, Benzamycin.RTM., is a topical gel containing 3% of erythromycin and 5% of benzoyl peroxide. Benzamycin.RTM., however, has several drawbacks. First, the product is supplied to pharmacies as a benzoyl peroxide gel in a first container and erythromycin powder in a second container. The product thus requires compounding by the pharmacist, who must (1) dissolve the erythromycin in alcohol, (2) add the erythromycin solution to the gel, and (3) stir until homogeneous in appearance. Second, the alcohol present in the composition as dispensed amounts to 16% of the total composition, which often proves to be excessively drying and irritating to the skin, particularly in combination with the benzoyl peroxide. Third, the composition as dispensed by the pharmacist (i.e., after reconstitution or compounding) lacks the stability necessary for extended storage at room temperature. The combination product can be stored under refrigeration for up to three (3) months.
Other efforts at improving the stability of combination products in particular have relied on the use of novel packaging which keeps the active agents separated to maintain stability until the time of use. However, compounding is still necessary at the time of dispensing and stability remains a problem, because the product must be used immediately upon being prepared.